Acoustic system



Sept. 18, 1928.

A. M L. NICOLSON ACOUSTIC SYSTEM Filed Feb. 23, 1923 A 0756/7/05: 61m 6/ [m 50/7, p 4 5,

Patented Sept. 18, 1928.

PATENT OFFICE.

UNITED STATES ALEXANDER MCI; NICOLSON, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ACOUSTIC SYSTEM.

Application filed February 23, 1923.

This invention relates to acoustic systems capable of reproducing faithfully and accurately all tones within the audible range.

In accordance with the features of this invention use is made of a plurality of freely moving sound reproducing devices differing in resonance and operating in response to a common source of sound wave energy. In its preferred form the invention provides a pair of freely moving diaphragms, one of which is particularly capable of reproducing vibrations low in the audible scale and the other particularly capable of reproducing vibrations high in the audible scale, both devices being operated simultaneously in response to a common source of sound wave energty.

Re erring to the drawings Fig. 1 shows a system employing one form of the invention.

Fig. 2 is an enlarged sectional view through the magnetic system of a sound translating device.

Fig. 3 shows an alternative arrangement in which the translating elements are operated b individual driving systems.

In t 1e drawing transmitter 4 of any suitable type is shown connected to the input of a vacuum tube 18 of any wellknown make through a suitable transformer 19 and across the output of the tube a sound translating device is connected, the magnetic system 8 of which is )referably of the type disclosed in Patent 0. 1,365,898 to II. C.

Egerton, January 18, 1921. The translating device may be supported in a standard which comprises an annular member 5 supported at its edge on a base 6 and to which the bracket 7 carrying the magnetic system 8 is secured. The diaphragm 9 which in its preferred form comprises two cones of sheet material such as fibre or paper joined together at their bases and supported freely in the annulus 5 by resilient membe s 10.

The diameter of the diaphragm 9 is preferably about one-fourth the length of the wave of the lowest frequency which it is desired to reproduce. A diaphragm of this shape and diameter is particularly efficient in the reproduction of tones low in the audible range. The diaphragm 9 is attached to the armature 11 by means of a link 12 which extends in the opposite direction and carries thereon a second and smaller diaphragm 18 which is preferably Serial No. 620,721.

conical in shape and made of some light material such as sheet fibre or paper. The size and structure of the diaphragm is such that it is particularly efficient in the reproduction of vibrations of high frequencies. The combination therefore of the two diaphragms of different characteristics, provides an acoustic system having a uniform response to all tones of importance in music and speech. The diaphragm 13 may be, either a single cone as shown or a double cone of similar structure as the diaphragm 9 and owing to its lightness it may be supported solely by the link 12 of the magnetic device 8.

In the modification shown diagrammatically in Fig. 3 the high and low frequency translating devices 14 and 17 have distinctly separate magnetic systems connected in parallel. The high frequency translating device may consist of a receiver, preferably of the type disclosed in Patent No. 1, 365,898 to H. C. Egerton, January 18, 1921, provided with a suitable horn, and the low fre uency translating device consists prefera ly of a similar magnetic system driving a large double cone-shaped diaphragm supported in the same manner as shown in Fig. 1, instead of the usual small diaphragm. By providing separate magnetic systems for the translating devices controls 15 and 16 may be inserted in circuit in series with each device, thereby providing means for modulating the sounds from each and operating them at the same volume level, or featuring the high or low frequency sounds at will.

The invention claimed is 1. In combination in a loudspeaking sound-reproducing device, a plurality of freely moving large direct-acting diaphragms having widely different resonance characteristics and arranged to project sound waves into the same region of the atmosphere, and means for operating said diaphragms simultaneously in response to a common source of sound-wave energy.

2. In combination in a loud-speaking sound reproducing device, a plurality of freely moving large direct acting diaphragms having widely different resonance iharacteristics disposed in substantially parallel planes and arranged to project sound waves into the same region of the atmosphcre. means for operating said diaphragms sinmltaneously in response to a common low .uamwmwwwwaw w H is. .c H

source of sound wave energy, and means common to said diaphragms for connecting said diaphragms to said operating means.

3. In combination in a loud-speaking sound reproducing device, a freely moving large direct acting diaphragm resonant at a frequency low in the musical scale, a second diaphragm resonant at a comparatively higher frequency in the musical scale and arranged to project sound in the same region of the atmosphere as said first diaphragm, an actuating device, and means connecting said diaphragms to the device for simultaneously operating said diaphragms.

4. An acoustic device comprising two large direct acting sound reducing diaphragms having oppositely directed coaxial conical surfaces, means connecting the apices thereof, and means responsive to sound wave energy associated with said connecting means for o crating said diaphragms and disposed there ctween.

5. An acoustic device comprising two large direct acting sound producing diaphragms, said diaphragms being freely moving and conical in shape, means for operating said diaphragms, in response to a common source of sound wave energy, said means being disposed between said diaphragms and means connecting said diaphragms to said operating means whereby both diaphragms are driven simultaneously in the same direction.

6. An acoustic device comprising two large direct acting sound producing diaphragms, one of said diaphragms having a dished surface and a free vibratile periphery, a single actuating device disposed between said diaphragms, and means connecting said device with said diaphragms whereby said diaphragms are operated simultaneously.

7. An acoustic device comprising a plurality of large direct acting sound producing conical diaphragms having aligned axes and separated vibratile peripheries, an actuating device, and means connecting said device to said diaphragms for simultaneous operation.

8. A sound reproducing device comprising a plurality of coaxially arranged conical sound radiating elements of different sizes, having their apices and outer edges spaced apart, and driving means common to said sound radiating elements for actuating them.

9. A sound reproducing device comprising a plurality of coaxially arranged diaphragms of different sizes, and means common to said diaphragms and connected thereto for driving them, said diaphragms being spaced apart at their outer edges and at their points of drive and having one face of each of them cxposeddirectly to the surrounding air.

In witness whereof, I hereunto subscribe my name this l9thday of February A. D.

ALEXANDER MoL. NICOLSON. 

